open

Mac OS X has an open command-line utility that I use extensively from the terminal. If ever I need to open a directory or any file with its default application, I just simply type open file and there is no need to open Finder and traverse to the directory.

# open a finder window in current directory
$ open . 

$ open http://google.com

$ open image.jpg

In Linux, you can get the same functionality with gnome-open:

# ~/.bash_profile
$ alias open=gnome-open

$ open http://segv.me

# open nautilus window in current directory
$ open .

man open
man gnome-open